Writing on the sand reads "You're gonna need a bigger boat" as state police looked for a Great White Shark spotted near Duxbury Beach in Massachusetts.

Shark Briefly Forces Massachusetts Beach-Goers Out of Water

A shark sighting prompted authorities to order swimmers out of the water for about two hours at a Massachusetts beach Monday. State police told NBC News that what looked like a 15-foot-long great white was spotted by a patrol helicopter near Duxbury just moments after a crew member said, "I wonder if we can find a shark off the coast during our patrol."

State police later tweeted that the shark had likely moved to deeper waters. The beach was reopened at 4 p.m. ET, with local authorities warning, "Swim at your own risk." At least four great whites were spotted off the coast of Cape Cod, just 40 miles south of Duxbury, a week before Monday's sighting, according to NBC-affiliated New England Cable News.